P10- Forces and motion Flashcards
what is resultant force?
when multiple forces act on an object, they can add together or subtract from each other until there is an equivalent of just one force acting in a single direction
what does the size of an arrow show on a free body diagram?
relative magnitudes
what does the direction of an arrow show on a free body diagram?
direction
what is the equation for resultant force?
resultant force(N)= mass(kg) x acceleration(m/s^2)
What is newton’s first law?
According to Newton’s first law of motion, an object remains in the same state of motion unless a resultant force acts on it. If the resultant force on an object is zero, this means:
:a stationary object stays stationary
:a moving object continues to move at the same velocity (at the same speed and in the same direction)
What is Newton’s second law?
if a resultant force acts on an object it will accelerate. acceleration is proportional to the force. links to the equation for resultant force
What is Newton’s Third Law?
for every equal action, there is an equal and opposite reaction.
what is the equation for work done?
work done(j)= force(N) x distance(m)
Required Practical: ACCELERATION
trolley has a piece of card which has a gap that will pass through the light gate and input this into the datalogger- ligth gate can measure velocity.
connect trolly to a piece fo string that goes over a pulley and is connected on the other side to a mass hanger.
weight of mass hanger and masses on it will provide the accelerating force equal to the mass of the hook x acceleration due to gravity(weight=mass x gravitaional field strength)
weight of mass hanger and masses accelerates both the trolley and masses, so you are investigating the acceleration of the system.
have a starting point of the trolley so it is always travelling at the same distance each time.
record the acceleration measure by the light gate as the trolley passes through it.
repeat twice to get average
in the acceleration practical to investigate the effect of mass what do you do?
add masses to only the trolley and record the average for each mass
a=F/m (mass of system increases but force applied is the same)
in the acceleration practical to investigate the effect of force what do you do?
need to keep total mass the same so start with all the masses on the mass hanger and then move them one by one to the trolley and record average acceleration
F=mxa (not changing the mass just an increase in force)
Inertia
a measure of how difficult it is to change the velocity of an object
ratio of force over acceleration
weight
force acting on an object due to gravity
measure in Newtons, N, vector quantity
equation for weight
weight(N)= mass(kg) x gravitational field strength(N/kg)
terminal velocity
the object moves at a steady speed in a constant direction because the resultant force acting on it is zero
